ROCKLAND, Maine — A fire that destroyed a shed and threatened two adjacent residences Tuesday night is under investigation by the Rockland Police Department and the Maine fire marshal’s office.

Assistant Fire Marshal Adam Miceli said the fire is believed to have been caused by someone, but could involve anything from an accident to intentional setting.

The fire destroyed an 8- by 10-foot shed that contained mainly garden tools and a lawn mower, the assistant chief said. The fire also melted some vinyl siding on a garage that was attached to the home where the shed is located at 6 Berkley St.

The property is owned by William Anderson, the assistant chief said.

He said the department also had to douse water on a two-unit house located about 25 feet behind the shed because of the intensity of the fire.

The fire was spotted initially by a neighbor who was arriving home. The neighbor ran across the street and alerted the homeowner. Miceli said there were also several other 911 calls made by people who saw the flames.